Coating method



Oct. 2,1934. c; H. DENNIYSON I 1,975,195

COATING METHOD Filed July 14, 1931 INVENTOR 07/4/5755 H. Qf/V/V/Jfi/V ATTORN grea ed CIR-1.11934 t 1,975,195

- UNITED ST TES PATENT? OFF COATING METHOD Charles H. Dennison, Quincy, Mass., assignor to American Rubber Company, Cambridge, Mass.,' I a corporation of Massachusetts Application July 14, .1931, Serial No. 550,639

1 Claim. (01. 91-68) In the manufacture of coated sheets of matebetween in order to permit a regulated flow .of rial, particularly coated textile fabrics, it has been liquid coating composition. The bearing surfaces customary to use a doctor knife'with a straight, may be arranged at a slight angle to the travel smooth and continuous bearing edge arranged of the sheet but are preferably substantially par- 5 to press against the fabric. It is common to poallelwith it. Their purpose is to contact with sition abase roller or support undera doctorknife the sheet and continually hold the same a preof this character in order to provide a base surdetermined distance away from the inner surfaces face against which the fabric may be held during 0f h r ves, allowing the in OOmDOSitiDII the application of the coating materials to the to flow through the grooves, whose size governs opposite surface by the knife. Sometimes the the thickness of the application. fabric is passed under such a knife without using The invention may satisfactorily take the form a" supporting roll and subsequently pulled upof a threaded bar like that illustrated in the enwardly under tension in order to enable the knife larged elevation of Fig. 1. This may be mounted to frictionally engage the surface and scrape a on a base member in the manner shown in D coating composition thereagainst. These expedispective in Fig. 2. 70

ents have been satisfactory to some extent but Fig. 3 shows diagrammatically how the invencertain disadvantages have been manifestin their tion may be utilized in the coating of sheet maadaptation to commercial manufacture. If the ,terial. coating liquid is non-viscous and applied between The bar 1 may be provided with screw threads 3 a doctor knife and a supporting roll, it is quite and intermediate grooves 2, the top of the threads 75 likely to strike through the fabric and accumulate being preferably filed off as indicated in Fig. 1. on the supporting roll or surface, resulting in The bar may be mounted on a member 6 provided difficulty in handling as well as a faulty and with a groove 4 into which it may be fixed by undesirable product. On the other hand the suitable means. It is of course understood that .25 amount of coating material applied to. a fabric the bar 1 which is illustrated is merely a con- 80 by drawing it against a doctor knife of the charvenient way of making a grooved mechanism and acter described is limited by the tension required that any type of grooved spreader bar or strip to be placed upon the fabric in order to keep its which is provided with a proper number of grooves surface in continual contact with the edge. If of requiredsize and provided with suitable bearv a high degree of tension is used only a small ing surfaces maybe used without departing from amount of" coating material is actually applied, the principles herein laid down.

and it is necessary to build up a coating of de- Asin Fig.3 the sheet 'imay be led under adevice sired thickness by many operations. If a low 8 which feeds the desired amount of coating comdegree of tension is used, the fabric may not be position to a reservoir orzbank 9 of the composi- 35 positively held against the knife and-an uneven tion confined by the upper surface of the sheet coating may result; I material and by the spreader bar 1. This may be An object of this invention is to overcome the regulated so. that the composition collects in the difllculties above alluded to and to enable the space between the sheet '7 and the bar 1 but does application of more liquid coating material'than not flow over the stops or guides 10-providedat has heretofore been possible, onto an advancing each side of the apparatus. The sheet is drawn sheet and in one operation. under the spreader bar 1 and the coating compo- Another object A to make the amount of liquid sition is applied to the sheet at spaced intervals coating material ca able of application to sheets, by virtue of the grooves or channels in the for instance fabrics, independent of the tension spreader bar. The composition thus applied flows to which the fabric is subjected to press it against together in the form of a continuous uniform film 100 the applying means. 'during the travel of the sheet to a suitable drier Other objects and advantages of the invention shown diagrammatically at 11, and from which will more-clearly appear when reference ishad to the dried and coated sheet travels to a winding the following specification and claim. reel 12 which may be driven by suitable means The invention involves the .use of a spreading (not shown) for winding the coated material at a 105 device of novel nature which is constructed to uniform speed. The material may be festooned provide a discontinuous edge made up of a numin a drier by the use of well-known looping deber of bearing or doctor surfaces for contact with 'vices, if desired As an example a latex compothe materialtobe treated andanumber of grooves sition may be fed as the coating material and in of regulated width and depth arranged therethis case it is preferable to regulate the viscosity coating material and the size of the grooves, may

of the latex to an extent suflicient to enable it to flow together again after passage through the grooves or channels which distribute it in a'continuous uniform film. The height and width of the grooves may be adjusted'to give the required flow. Various factors such as the consistency of of course be varied to suit conditions, and these factors must be considered in connection with the specific type of materials treated.

It should be noted that the amount of coating composition thus applied in uniform manner to a sheet material is practically independent of the pressure of the sheet surface against the doctor bar, it beingmecessary only to nominally tension the material against the bar. As the amount of internal structure is not disturbed by appreciable friction against the bearing surfaces, the material easily flowing through the grooves and filling the spaces left by the bearing surfaces by virtue of the separate streams flowing together again.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

The process of forming a layer of liquid coating composition on travelling sheet material which comprises passing said sheet material under tension under a grooved spreader bar, supplying a' coating composition to a reservoir or bank of the same confined by the upper surface of the sheet and by the spreader bar whereby the coating composition-flows through the grooves of the spreader bar and is distributed upon the sheet at spaced intervals as the sheet travels under the spreader bar, and allowing the thus applied comv CHARLES H. DENNISON. 

